Wire tensioning device



March 19 1963 c. R. CARLSON ErAL 3,031,976

WIRE TENsIoNING DEVICE Filed June 2, 1961 3 Sheets-Sheet 1 NVEZLTO @JCHT-romyf March 19, 1963 Filed June 2, 1961 C. R. CARLSON ETAL WIRETENSIONING DEVICE w.. om E 02 i' YD Carl @mj Car/($911., :Donald.Nawkuusoyb Qmam e. mamada@ @cui @.Qof-nnenfk (y1 vromsfw March 19, 1963C. R. CARLSON Em 3,081,976

v WIRE TENSIONING DEVICE Filed June 2, 1961 3 Sheets-Sheet'l 3 WJ CarlQgg, Cavlqom :Donald L CNoLwKwLU-om Qllam I Qeddermk C5062 (DQ-Saunen.en.

United States Patent O 3,081,976 WIRE TENSIONING DEVICE Carl RayCarlson, Donald E. Hawkinson, William E.

Hedderich, and Joel A. Jannenga, Rockford, Ill., as-V The inventionrelates to a device for applying tension' to a strand of wire or'thelike and, more particularly, to a wire tensioning device adapted tobe used in conjunction with a clamp having a member movable in apredetermined direction to grip one end of the wire and maintain theapplied tension after the device is removed.

The general objectrof the present invention is to provide a novel deviceof the above character which in a single and simple operation applies apredetermined tension to `the wire and subsequently opera-tes the clampto grip the wire.

Another object is to provide in a tensioning device a novel chuck whichfacilitates insertion and gripping of the wire preparatory totensioning, postively grips the wire during tensioning, andautomatically releases the wire upon completion of the tensioningoperation and after the clamp has been operated to grip the wire.

A further object is to provide a tensioning device which automaticallyoperates the clamp after the desired tension has been applied and whilesuch tension is maintained, thus insuring that the proper tension isheld in the wire.

`Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in

which:

FIGURE 1 is a fragmentary elevational view of a tensioning deviceembodying the novel features of the present invention. FIG.`2 is anenlarged fragmentary sectional view taken along the line 2 2 in FIG. 1.l

FIG. 3 is an enlarged fragmentary sectional view taken along the line3-3 in FIG. 2 and showing the device during the tensioning operation.

FIG. 4 is an enlarged fragmentary section taken along the line 4-4 inFIG. 2.

FIG. 5 is a perspective view of the jaws of the chuck.

FIG. 6 is an enlarged fragmentary sectional view taken along the line6-6 in FIG. 2

, FIG. 7 is a diagrammaticview showing the hydrauli Vcircuit of thedevice.

As shownv in the drawings for purposes of illustration, theinvention isembodied in a device 10 for applying tension to steel rods or wires 11during the manufacture of Prefabricated concrete beams 12 (FIG. l) inwhich a plurality of pretensioned reinforcing members are embedded whilethe beams are being cast. Usuallyrsuch reinforcing members are stretchedbetween spaced supports such as I-beam posts 13 disposed Xon oppositesides of a continuous casting platform (not shown), each wire being heldsecurely at its ends by suitable clamps 14 mounted on the posts.

Herein, each of the clamps comprises a horizontally disposed body 15bolted at 17 to one of the posts 13 with a clamping mechanism at eachend of the body, the clamping mechanism including a wedge element 18slidable into and out of a slot 19 in the body to cam the adjacentserrated faces of blocks 20 together (see FIG. 7). One clamp of thistype is disclosed in our copending application, Serial No. 35,699 ledJuly 13, 1960, to which referen-ce is made for details of disclosure notcontained herein. One end of a wire to be tensioned is inserted in oneof the clamps, herein the one on the right in FIG. l,

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and the associated wedge 18 is shifted into its slot to lock the blocks20 against the wire. Then the opposite end of the wire is insertedthrough the opposite clamp and into the tensioning device 10 which drawsthe wire through the clamp and thereby applies the desired tension. Whenthe wedge is shifted into its locking position, the Wire will be heldsecurely while the concrete beam 12 is cas-t and hardens.

Preferably, the tensioning dev-ice is mounted on a fiat, lgenerallyrectangular `base 21 adapted to be disposed on one side of the clamp andmeans is provided to support the base against movement toward the clampas tension is applied to the wire. In this instance, this meanscomprises a plate 22 secured to the base along one side thereof with aprojecting portion 23 extending past the end 26 of the base and over theclamp body. Formed in the underside of this end portion is a downwardlyopeningy slot` 24 adapted to t snugly over the clamp so that the wallsof the slot abut against opposite sides of the clamp and brace the baseagainst end'wise movement relative to the clamp. A finger 25 joined tothe base adjacent the other side thereof lies against the top of thebody and prevents tipping of the base from side to side.

As shown in FIG. 3, a reciprocating hydraulic actuator 27 is mounted onthe base to apply tension of the desired magnitude to the Wire. Thisactuator preferably comprises a cylinder 28 formed in a housing 29secured -to the base adjacent the end 30 thereof opposite the clamp witha piston 31 fitted in the cylinder for sliding toward and away from theclamp. The piston rod 32 projects through the wall 33 of the housing andis connected at its outer end to a chuck 34 slidable on the base andadapted -to receive and grip the end of `the wire. In this instance, theend of the rod secured to the chuck is made hollow to accommodateVarying lengths of wire. Thus, when pressure fluid from a suitablesource such as a pump 35 (FIG. 7) is admitted through a line 37 to oneend of the cylinder, herein the right end as viewed in FIG. 3, thelactuator tensions the wire by drawing it through the clamp, themagnitude of the applied tension depending, of course, upon the pressuredeveloped in the cylinder 28. When the desired tension has been applied,the wedge 18 may be shifted into its locking position to engage theclamp.

In one of its aspects, lthe present invention contemplates a novel chuck34 which facilitates insertion of the wire 11 into the device andgripping of the wire preparatory to tensioning, positively grips thewire during the tensioning stroke of the piston 31, and automaticallyreleases the wire upon completion of the tensioning operation. Toachieve these ends, the chuck is constructed land mounted in a novelmanner so that it is clamped tightly against the wire as an incident tothe beginning of the tensioning stroke of the piston and is openedautomatically during the return stroke.

Herein, the chuck 34 is mounted in a block 38 slidable on the basetoward and away from the clamp, the block ibeing formed adjacent one endwith a vertical bore 39 into which the end of the rod 32 projectsthrough the side wall 40 of the block. Nuts 41 may be threaded onto therod and tightened against opposite sides of the wall 40' to secure theblock for reciprocating with the rod. Extending through the block fromthe other side wall of the bore 39 to the side of the block adjacent theclamp is an opening 42 with walls tapering toward the clamp. A pluralityof laterally separable jaws 43 (see FIG. 5), the outer sides of whichcooperate to form a `correspondingly tapered body 44,` are slidablelongitudinallyin this opening and .adapted to lbe disposed around theend of the wire. In this instance, there are three such jaws and -boththe outer surfaces of the jaws and the wall of the opening are generallyfru-stro-conical in shape, lateral separation of the jaws `being limitedby a snap ring 45 seated in an annular groove encircling a cylindricalneck 47 formed on the larger end of the body and concentric therewith.This ring also prevents axial sliding of the jaws relative to eachother.

Normally, the block 38 is positioned against a stop formed by the side48 of a lug 49 secured to the base adjacent the end 26 with the smallerends of the jaws abutting lagainst the side 48 of the lug around a notch50 formed in the top of the lug and communicating with the opening `42,as shown in FIG. `6. In this position, the jaws tit loosely in the blockand, therefore, are free to separate laterally and receive the free endof the wire which Imay be inserted into the chuck through the notch 50.To guide the wire between the jaws, the inner edges ofthe jaws may bebeveled `as at 51 (FIG. 6).

Closure of the chuck to grip the wire preparatory to tensioning thereofis accomplished automatically as `an incident to the beginning of thetensioning stroke of the piston 31 by means of a coiled spring 52'compressed between the larger ends of the jaws and a plug 53 threadedinto the adjacent end of the opening `42. Thus, during the initialmovement of the block 38 away from the stop, the jaws are spring-pressedthrough the opening land toward the stop so that the tapering wall 42coacts with the taper of the jaws to cam the latter together and intogripping engagement with the wire. Continued movement of the block Iawayfrom the clamp produces Ia frictional drag Ibetween the jaws and thewire which tends to draw the jaws through the opening. Consequently, thejaws are clamped even more tightly against the Wire during tensioning.

Means is provided to open the chuck automatically after the propertension has been applied and the clamp 14 has been engaged. In thisinstance, this means comprises a coiled compression spring 54 (FIG. 3)which urges the block back to its normal position against the stop andvcoacts with the stop to press the jaws back into their retractedposition (FIG. 6). As shown in FIG. 3, the spring 54 is confined withinthe cylinder 28 between the piston 31 and the inner end of an adjustingscrew 55 threaded through the end plate 57 of the cylinder. With thisarrangement, the spring 54 is compressed during the stroke of the pistonand, upon release of the pressure iiuid, returns the piston to itsinactive position thereby opening the jaws so that the wire may beWithdrawn from the chuck.

Pressure tiuid from the pump 35 is delivered to the line 37communicating with the cylinder 28 through a suitable control valve, inthis instance a selectively operable spool-type Valve 58 mounted in acasing 59 on the housing 29. As shown in FIG. 7, the spool 60 isshiftable back and forth between two positions in the casing by means ofa hand lever 61 pivotally mounted on the exterior ofthe housing 29. Inone of its positions, the spool connects the line 37 with the output ofthe pump 35 to activate the tensioning actuator 27 and in its other,normal position, the Valve blocks the pump output and connects the line37 with a line 62 communicating with the pump reservoir.

The invention also contemplates a novel tensioning device whichautomatically operates the clamp 14 when the desired tension has beenapplied and while such tension is maintained by the actuator 27, thusautomatically completing the operation and insuring that the propertension is held in the wire. For this purpose, the device includes asecond actuator 65 activated in response to a predetermined pressure inthe cylinder 28 andoperable to shift the wedge element 14 into itsclamping position. Herein, the second actuator 65 comprises a cylinder67 formed in the housing 29 alongside the cylinder 28 with a plunger 68reciprocable in the cylinder 67 toward and away from the clamp.

As shown in FIG. 4, the plunger 68 comprises a sleeve 69 telescopingsnugly with the cylinder 67 and having a closed end projecting outwardlyfrom the cylinder. Threaded into the outer end of the plunger is a bolt70 whose head abuts against `one end 71 of a rod 72, the latter beingjournaled for sliding longitudinally back and forth in a passage 73forming a guideway through a support 74 fast on the base adjacent theend of the wedge'. The rod 72 projects from opposite sides of thesupport and a spring 75, coiled around the rod between its head 71 andthe side of the support, urges the rod toward the plunger as shown inFIG. 2. An extension spring 77 fastened to the end wall 7S of thecylinder 67 and to the closed end of the plunger urges the latter intoits retracted position. When pressure fluid is directed into thecylinder 67, however, the plunger is extended and presses the end 79 ofthe rod against the wedge to shift the latter into its locking position.When the fluid is released, the two springs 77 and 75 return the plungerand the rod to their retracted positions.

Means responsive to a predetermined pressure in the cylinder 28 isprovided to activate the actuator 65 and lock the clamp automaticallywhen the desired tension has been applied to the wire. Herein, thismeans comprises a pressure-responsive sequence valve 80 (FIG. 7)disposed in a conduit communicating between the cylinders 28 and 67, theconduit being formed by branch line 81 from the line 37 and a, secondbranch line 82 leading from the line 81 to the cylinder 67. The valve 80preferably is. `a spring-loaded plunger 83 normally closing branch line81. When the pressure in the cylinder 28 and the line 37 equals thevalve setting, which may be adjusted as desired by means of a screw 84,the valve opens to admit fluid into line 82 thereby to move the plunger69 and the rod 72 toward the wedge.

It will be apparent that the spring loading of the valve S0 maintainsthe pressure in the tensioning cylinder 28 as iiuid flows into thecylinder 67, thus holding the proper tension while the clamp is beingclosed. After the wedge is engaged, the control lever 61 may be returnedto its normal position in which the pump output line is closed and thelines 62 and 82 are open to return iiuid exhausted from the cylinders tothe reservoir. Thus, the tensioning operation is completed and thedevice rnay be positioned for insertion of the next wire.

We claim as our invention:

l. In a device for tensioning Wire and the like and subsequently movinga member of a clamp in a predetermined direction to grip the wire andmaintain the tension, the combination of, a base adapted to be disposedon one side of the clamp, a plate secured to said base adjacent one endwith a projecting end portion adapted to extend over the clamp, saidportion being formed with a slot therein adapted to fit snugly over theclamp whereby said' plate supports the base on the clamp, a blockslidable on said base toward and away from said one end, a stop mountedon said base adjacent said one end, said block normally abutting againstsaid stop and having an opening therethrough generally paralleling thewire and tapering toward the stop, a plurality of laterally separablejaws disposed within said opening and slidable longitudinally thereoftoward and away from said stop, said jaws being adapted to receive afree end of the wire through a slot formed in the stop and communieatingwith said opening, spring means urging said jaws toward said stop, theouter walls of said jaws being tapered toward said stop, a firstreciprocating hydraulic actuator connected to said block and operablewhen activated to slide the latter away `from the stop whereby said jawsslide in said opening relative to said block, the wall of the openingcoacting with the walls of said jaws to cam the latter together and intogripping engagement with the wire thereby to tension the wire, a secondreciprocating hydraulic actuator for moving said member in saidpredetermined direction, a source of iiuid under pressure, a line fordelivering said uid to said iirst actuator to activate the latter, aconduit communieating with'both-of said actuators, anda pressureref-sponsive valve in said conduit normally closing the latter andoperable when a predetermined pressure is developed -in said rstactuator to open lthe conduit and admit said -tluid` `to saidv secondactuator while maintaining said subsequently moving a member of a clampin a predetermined direction to grip `the wire and maintain thetension,vthe combination of, a base adapted to be disposed onone sideofthe clamp, means supporting said base against movement towardtheclamp, a stop mounted lori saidfbase, fa Ablock slidable on said basetoward and awayfrom the clamp and normally abutting against the side ofsaidA stop opposite the clamp, said block having an opening therethroughwith walls tapering toward said stop, a plurality of laterally separablejaws slidable longitudinally in` said opening and adapted Ito -bedisposed around the wire, said jaws being tapered toward and normallyabutting against said stop, spring means'urging said jaws toward saidstop thereby to close the jaws and grip the wire as said block slidesaway from the stop, a first reciprocating hydraulic actuator connectedto said block and operable when activated to close said jaws and mJve4the yblock away from theV clamp thereby to grip and tension the wire, asecond actuator operable when activated to move the member in saidpredetermined direction, means for delivering pressure fluid to said rstactuator to activate the latter, and spring means urging said blocktoward said stop whereby said jaws are pressed against said lstop andthe wire is released when said pressure fluid is released from saidiirst actuator.

3. In a device for tensioning wire and the like and subsequently movinga member of a clamp in a predetermined `direction to grip the wire andmaintain the tension, the combination of, a base adapted to be disposedon one side of the clamp, means supporting said base against movementtoward the clamp, a stop mounted on said base, a block slidable on saidbase toward and away from the clamp and ynormally abutting against theside of said stop opposite the clamp, said block having an openingtherethrough with walls tapering toward said stop, a plurality oflaterally separably jaws slidable longitudinally in said opening andadapted to be disposed around the wire, the outer walls of said jawsbeing tapered toward and normally .abutting against said stop, springmeans urging said jaws toward said stop thereby to close the jaws andgrip the wire as said block slides away from the stop, a rstreciprocating hydraulic actuator connected to said block and operablewhen activated to close said jaws and move the block away from the clampthereby to grip and tension the wire, a second actuator operable whenactivated to move the member in said predetermined direction, means fordelivering pressure fluid to said rst actuator thereby to grip andtension the wire, and means responsive to a predetermined pressure insaid iirst actuator to activate said second actuator.

4. In a device for tensioning wire and the like and subsequently movinga member of a clamp in a predetermined direction to grip the wire andmaintain the tension, the combination of, a base adapted to be disposedon one side of the clamp, means supporting said base against movementtoward the clamp, a stop mounted on said base, a block slidable on saidbase toward and away from the clamp and normally abutting against theside of said stop opposite the clamp, said block having an openingtherethrough tapering toward said stop, a plurality of laterallyseparable jaws slidable longitudinally in said opening toward and awayfrom said stop and adapted to be disposed around the wir'e, the outerwalls of said jaws being tapered toward said stop, spring means urgingsaid jaws toward said stop thereby to cam the jaws together and intofrictional engagement with the wire as said block slides away from thestop, said stop normally blocking said jaws against sliding in saidopening, a iirst reciprocating hydraulic actuator connected to saidblock and operable when activated to close said jaws and slide the blockaway from the clamp thereby to grip and tension the wire, a secondactuator operable when `activated to move the member in saidpredetermined direction, means for delivering pressure fluid to said rstactuator thereby to grip and tension the wire, and means responsive to apredetermined pressure in said first actuator to activate said secondactuator.

5. In a device for tensioningwire andthe like and -subsequently moving amember of a clamp in a predetermined direction to grip the wire andmaintain the tension,` the combination of, a base adapted to be disposedon one side of the clamp, means supporting said base against movementtoward the clamp, a chuck mounted on said base for sliding toward andaway from the clamp and adapted to receive and grip one end of the wire,a first reciprocating hydraulic actuator connected to said chuck andoperable when activated to close said chuck and move the same away fromthe clamp thereby to grip `and tension the Wire, a second reciprocatinghydraulic actuator for moving said member in said predetermineddirection, a source of tluid under pressure,

`a line lior delivering said tluid to said iirst actuator thereby to-grip and tension the Wire, a conduit communicating with both of saidactuators, and a pressure responsive valve in said conduit normallyclosing the latter and operable when a predetermined pressure isdeveloped in said first actuator to open the conduit and admit saidfluid to said second actuator while maintaining said pressure in theiirst actuator.

6. In a device for tensioning wire and the like and subsequently movinga member of a clamp in a predetermined direction to grip the wire andmaintain the tension, the combination of, a base adapted to be disposedon one side of the clamp, means supporting said base against movementtoward the clamp, a chuck mounted on said base for sliding toward andaway from the clamp and adapted to receive and lgrip one end of thewire, a first reciprocating hydraulic actuator connected to said chuckand operable when activated to close said chuck and move the same awayfrom the clamp thereby to grip and tension the wire, a second actuatoroperablel when activated to move the member in said predetermineddirection, means for delivering pressure fluid to said irst actuatorthereby to grip and tension the wire, and means responsive to apredetermined pressure in said rst actuator to activate said secondactuator.

7. In a device for tensioning wire and the like, said wire having an endxed relative to the device and a free end, the combination of, a base,means supporting said base adjacent said free end and against movementtoward said iixed end, a block slidable on said base toward and awayfrom said Xed end, a stop mounted on said base between said block andsaid tixed end, said block normally abutting against said stop andhaving an opening therethrough generally paralleling the wire andtapering toward the stop, a plurality of laterally separable jawsdisposed within said opening and slidable longitudinally thereof towardand away from said stop, said jaws being adapted to receive the free endof the wire through the stop, spring means urging said jaws toward saidstop as said block slides away from said stop, the outer walls of saidjaws being tapered toward the stop v and coacting with the wall of saidopening to cam the against the stopwhen said pressure iluid is released`thereby to open said jaws.

8. In a device for tensioning wire and the like, said wire having an endfixed relative to the device and a free end, the combination of, a base,means supporting said base adjacent said free endy and against movementtoward said fixed end, a block slidable on said' base towardv and awaylfrom said xed end, a stop mounted on said base between said block andsaid fixed end, said block normally abut-ting against said stop andhaving an opening therethrough generally paralleling the wire andtapering toward the stop, a plurality of laterally separable jawsdisposed within. saidV opening and slidable longitudinally thereoftoward and away from said stop, said jawsy being adapted to receive thefree end of the wire through the stop, spring means urging said jawstoward said stop as said block slides away `from the stop, the outerWalls of said jaws being tapered toward' said stop and coacting with`the wall of said opening to cam the jaws together and intogrippingengagement with the wire, and selectively operable means for slidingsaid block away from said stop therebyv to close said jaws and tensionthe wire.

9. In a device for tensioning wire andthe like, said wire having one`end fixed relative to the device and a free end, the combination of, abase, means. for supporting the base in a fixed position relative to thewire, a block slidable back and forth on the base along a pathparalleling the wire, a stop formed onl said base between said block andsaid xed end, saidv block normally abutting against said stop and havinga frustro-conical opening therethrough generally paralleling the wireand tapering toward the stop, a plurality of laterally separable jawsdisposed within said opening and having outer walls forming a generallyfrustro-conical body slidable longitudinally in said opening to presssaid jaws together as they' slide toward said stop relative to. saidblock, said jaws normally abutting at one endy against said stop arounda slot therein and being held loosely within said opening to receive thewire through said slot, spring means urging said jaws toward said stopthereby to bring the jaws intogripping engagementy with the wire as theblock slides away from the stop, and selectively operable means forsliding said block away from the wire thereby to close said jaws andtension the wire.

References Cited in the le of this patent UNITED STATES PATENTS

6. IN A DEVICE FOR TENSIONING WIRE AND THE LIKE AND SUBSEQUENTLY MOVINGA MEMBER OF A CLAMP IN A PREDETERMINED DIRECTION TO GRIP THE WIRE ANDMAINTAIN THE TENSION, THE COMBINATION OF, A BASE ADAPTED TO BE DISPOSEDON ONE SIDE OF THE CLAMP, MEANS SUPPORTING SAID BASE AGAINST MOVEMENTTOWARD THE CLAMP, A CHUCK MOUNTED ON SAID BASE FOR SLIDING TOWARD ANDAWAY FROM THE CLAMP AND ADAPTED TO RECEIVE AND GRIP ONE END OF THE WIRE,A FIRST RECIPROCATING HYDRAULIC ACTUATOR CONNECTED TO SAID CHUCK ANDOPERABLE WHEN ACTIVATED TO CLOSE SAID CHUCK AND MOVE THE SAME AWAY FROMTHE CLAMP THEREBY TO GRIP AND TENSION THE WIRE, A SECOND ACTUATOROPERABLE WHEN ACTIVATED TO MOVE THE MEMBER IN SAID PREDETERMINEDDIRECTION, MEANS FOR DELIVERING PRESSURE FLUID TO SAID FIRST ACTUATORTHEREBY TO GRIP AND TENSION THE WIRE, AND MEANS RESPONSIVE TO APREDETERMINED PRESSURE IN SAID FIRST ACTUATOR TO ACTIVATE SAID SECONDACTUATOR.